Otitis media is an infection of the middle ear that occurs primarily in children. Left untreated, the disease can result in hearing loss and developmental delays. It is estimated that otitis media accounted for 31 million of the 130 million office visits for respiratory diseases in the period from 1977–87. Recent data indicate that suppurative and unspecified otitis media rank first in the list of the 30 most common diagnoses requiring a physician's office visit for patients up to age 24. Over one billion dollars per year is spent on treatment of this disease and the related loss of income for working parents is estimated to be between $300 and $600 million. Approximately 83% of all children will have had at least one episode of acute otitis media by three years of age. Non-typable strains of Haemophilus influenzae account for 25–30% of all cases of otitis media, 53% of recurrent otitis media, and are the primary pathogens isolated from 62% of cases of chronic otitis media with effusion. Although non-typable Haemophilus influenzae (NTHi) are primary pathogens in otitis media, neither the pathogenic mechanisms nor the host immunological response has been fully defined for this disease.
Fimbriae, which are surface appendages found on non-typable Haemophilus influenzae, are produced by 100% of the bacteria recovered from the middle ears and nasopharyngeal region of children with chronic otitis media. A vaccine comprised of fimbrin, a filamentous protein derived from the fimbriae of non-typable Haemophilus influenzae was previously developed and is useful in studying, preventing, or reducing the severity of otitis media. However, existing methodologies to isolate fimbrin protein from the bacterial outer membrane are tedious and time-consuming. Similarly, purification of fimbrin expressed by the fimbrin gene in other host vector, is also tedious due to the homology between the fimbrin protein and the outer membrane proteins of the host vector.
A strategy with other bacterial species has been to use an alternative immunogen having relatively short linear peptides. However, such alternative immunogens are of limited value since antibodies to such alternative immunogens frequently fail to recognize the native pathogen.
It would be desirable to have an immunogenic composition to immunize animals against non-typable Haemophilus influenzae which does not depend on tedious purification techniques.